An experimental comparison of gas back mixing in fluidized beds across the regime spectrum
Chemical Engineering Science, 1989, 44(8): 1697-1705
Jinghai Li, Herbert Weinstein
An investigation of gas backmixing in fluidized beds spanning the entire range from the bubbling regime to the dilute transport regime was conducted using continuous injection of a helium tracer. The focus was to compare backmixing levels in the different regimes. While time averaging at a point averages over the phase heterogeneities in the bubbling and slugging regimes, it does not average these out in the high-velocity regimes of turbulent and fast fluidization where the heterogeneities are distributed in space rather than time. It is also shown that, in the bubbling and slugging regimes, the concentration of backmixed tracer is almost independent of the gas velocity while, in the turbulent and fast regimes, the concentration is strongly dependent on the gas velocity.